This invention relates to the fluid catalytic conversion of hydrocarbons and the improved method and use of a particular feed atomizing injector or nozzle means for obtaining intimate atomized contacting of a gas oil and/or a high boiling residual oil feed material with finely divided fluid catalyst particles. More particularly, the contact conditions are selected to obtain substantially instantaneous vaporized-atomized contact of the charged oil feed with fluid catalyst particles of desired elevated temperature for conversion in a hydrocarbon conversion zone to hydrocarbon products comprising gasoline, gasoline precursors, and obtain a reduction in dry gas and coke make. The oil feed which may be processed by the technique of the invention is a portion of a crude oil such as a gas oil with or without a higher boiling hydrocarbon feed portion which may comprise metallo-organic compounds and substantial Conradson carbon producing components boiling above about 1025.degree. F. Such a hydrocarbon feed may be high boiling residual oil portions of crude oil which are referred to in the literature by a number of different terms as a low API gravity oil, topped crude, reduced crudes, heavy residual oils, vacuum gas oil comprising resid components, and high boiling residual hydrocarbons comprising metallo-organic compounds. These are among the several terms used in the prior art.
In the prior art of U.S. Pat. No. 3,547,805 the hydrocarbon oil feed is charged to the system by injecting it by an annulus surrounding a stream of water. This system is concerned with atomizing the oil feed and mixing it with steam.
U.S. Pat. No. 3,152,065 discloses feed injector arrangements which include an inner pipe for passing steam and an outer pipe forming an annulus for passing oil feed which is mixed in a smaller diameter opening in the end of the outer pipe displaced apart from the open end of the inner steam pipe. The patent also discloses placing curved stator vanes in the annulus adjacent to the end of the steam pipe. The feed nozzle combination may be used in the bottom of a riser or in the wall of the riser above the catalyst inlet thereto.
U.S. Pat. No. 3,654,140 is directed to a novel cat cracking oil feed injector design concurrently feeding steam to the injection zone in a volumetric ratio of steam to liquid hydrocarbons ranging from about 3 to 75, thereby imparting to the resulting mixture an exit velocity relative to the fluidized catalyst of at least about 100 feet per second whereby the oil feed stock is essentially completely atomized at the nozzle exit forming droplets less than about 350 microns in diameter. The nozzle exit of each of FIGS. 1 and 2 are shown extended a substantial distance into the reaction zone where upflowing dispersed phase catalyst can be attrited and/or erode the nozzle end.
U.S. Pat. No. 3,812,029 contemplates a nozzle arrangement similar to U.S. Pat. No. 3,071,540 except that the outer tube is used to inject water at a temperature and flow rate lower than that of oil feed in the center tube. An article in the Oil and Gas Journal for Mar. 30, 1981 entitled, "Burst of Advances Enhance Cat Cracking", by D. F. Tolen, reviews in considerable detail some problems facing modern day refiners processing residual oils and comprising metal contaminants and Conradson carbon producing components boiling above vacuum gas oils. The subjects briefly discussed include catalysts suitable for resid cracking in the presence of metal contaminants; the effect of metal contaminants on product selectivity; the addition of steam and/or water with the feed; catalyst regeneration; feed quality; combustion promoters used during regeneration of the catalyst to remove carbonaceous deposits and obtain desired regeneration catalyst temperature profiles and identifies problems associated with sulfur and nitrogen oxides in the feed and combustion flue gases. This article further identifies the need to obtain good mixing of the feed with catalyst in a riser reactor. In this catalytic-hydrocarbon conversion environment, good mixing is said to reduce gas make, increase gasoline selectivity, and improve catalytic cracking in preference to thermal cracking and reduce carbon formation.
The prior art identified operating parameters are intended to accelerate a mixture relatively uniformly with a feed vaporization section of a riser reactor zone in a minimum time frame and thus enhance rapid heat transfer from hot catalyst particles to charged feed, preferably atomized, and thus prevent localized enhanced catalyst to oil ratios contributing to a dense catalyst bed phase. That is, the operating conditions and methods for implementing are selected to ensure a relatively dilute phase suspension formation between catalyst particles and atomized oil feed for vaporized conversion transfer through a riser conversion zone. Such dilute catalyst phase operations include catalyst particle concentrations in the range of 0.5 to 10 pounds per cubic foot and preferably not above about 5 pounds per cubic foot.